I've had various problems with both of my FOB's lately, and finally decided to crack them open to figure out what's up. Both of them (one of which has sat in my cupboards 99% of the time, had the same issue.
The little black steel contact glued to the back of the rubber had come off, and was floating inside of the unit. On the FOB that sits in my house almost all the time, there was a blotch of the glue right on the circuit board as well! This may explain the random work/not work condition, unlocking, etc.
I just tried a drop of superglue between the contact and the rubber... not sure if this is the right glue for the job, but it's what I had sitting at my desk at work.
Anyone else have this problem? Anyone have a better solution than superglue?